CD44 and cancer: Two of these biomarkers are CD44 (found on CSC in cancers of the colon, esophagus, stomach, pancreas, breast, brain, lung, ovaries, prostate, liver, and the head and neck region) and CD133 (found in cancers of the colon, esophagus, stomach, pancreas, brain, lung, ovaries, prostate, liver, skin, and the head and neck region) (38, 61).